UV Unwrap

In Maya and ZBrush

Info

This page will go over UV unwrapping using the strengths of both Maya and ZBrush. ZBrush’s Auto Unwrapping tool UV Master is superior to Maya so in many situations we can simply send the file to Zbrush to unwrap there.

 

Overview (2 mins)

1. Choose seams in Maya and cut up
2. Send obj to ZBrush (note ZBrush won’t accept ngons)
3. Open in ZBrush and use ZPlugin > UV Master. And Auto Unwrap
4. Send back to maya and transfer the UVs onto the original Object with ngons
5. Rearrange UVs (if required)
6. Use the hypergraph to connect the UVs onto a skinned mesh without affecting history (if required)
We use Maya to prep our UVs by choosing seams and ZBrush to Unwrap. Then come back to Maya to tweak UVs once they’ve been unwrapped.
Maya unfortunately is terrible at auto unwrapping, Zbrush has a great auto unwrapping tool built into it, possibly the best around for a one click solution.

Video 1.1: Quick Overview (2:18 mins)
 

Video Notes

1. Choose seams in Maya and cut up
2. Send obj to ZBrush (note ZBrush won’t accept ngons)
3. Open in ZBrush and use ZPlugin > UV Master. And Auto Unwrap
4. Send back to maya and transfer the UVs onto the original Object with ngons
5. Rearrange UVs (if required)
6. Use the hypergraph to connect the UVs onto a skinned mesh without affecting history (if required)
We use Maya to prep our UVs by choosing seams and ZBrush to Unwrap. Then come back to Maya to tweak UVs once they’ve been unwrapped.
Maya unfortunately is terrible at auto unwrapping, Zbrush has a great auto unwrapping tool built into it, possibly the best around for a one click solution.

 

Maya Preparation (35 mins)

In this section we’ll prepare the mesh for the auto unwrap in zBrush by selecting the seams and preparing the mesh.

Video 2.1: Choosing The Seams in Maya (8:03 mins)
 

Video Notes

Meshes need to unwrap flat therefor we must select the seams so that they can be made flat. For example a cylinder must have a seam along it’s length to unrwrap properly. We need to think about our models in this way while selecting seams. Be prepared to make some mistakes and try different options.
1. Create a blank set of UVs by Planar projecting from any view
(Polygon Menu) > Create UVs > Planar Mapping
2. Select the edges for seams.
3. Open the UV window
Window > UV Texture Editor (or press 9)
4. Cut the seams
Polygons > Cut UV Edges
5. Use “select shell” to break apart the UVs
– use the Move UV Shell Tool (2nd icon across from top) or Tool > Move UV Shell Tool
– or select a vertex, right click, select > select shell
*Tip 1: We can break up the mesh part by part, no need to do it in one go. We can also select the shell in face mode and isolate it in the viewport to access tricky areas or to hide areas that are already done.
*Tip 2: We also can skip this stage as ZBrush can automatically select seams. I prefer to know exactly where my seams will go by selecting them first.

Video 2.2: Sending To ZBrush (8:03 mins)
 

Video Notes

If the unfold fails or could be better it’s still good to know how to go to ZBrush as it’s algorithm is still the most reliable, but 95% of the time the Maya unfold will work perfectly now. If unfolding in Maya skip straight to step 7… “7. Tweak UVs in Maya”.
(CONTINUED for ZBrush workflow)
ZBrush doesn’t handle NGons or faces with more than 5 faces. This isn’t a problem as we can divide those faces temporarily and then transfer the UVs back onto our original mesh once back in Maya.
** Please note: You need to have the mesh unparented and zeroed on translation and rotion with a scale of 1 before you send/export as ZBrush/objs can reassign the scale/transform of your obj when you bring it back.
Two options for sending objects to ZBrush
1. Manual
Simply export objs and import into ZBrush, this is probably easiest as ZBrush will automatically divides NGons (polys with more than 4 sides).
2. GoZ
Objects with Quads and tris only can be sent using GoZ, we can remove ngons on our models first using mesh>cleanup, it’s best to duplicate the mesh while doing this.

Video 2.3: Maya 2015 Update (19:36 mins)
 

Video Notes

Please note that in Maya 2015, Maya’s unwrap has improved it’s still not as good as ZBrush but it’s good to know about it’s features. Also see
James Taylors tutorial here for more info though this ZBrush workflow is still the easiest and simplest.

 

Unwrapping In ZBrush (1 mins)

Unwraping in ZBrush is easy.
1. Go to Zplugins > UV Master
2. Make sure “Symmetry” and “Use Existing UV Seams” is on
3. Click Unwrap
To Check the UVs
1. Go to Zplugins > UV Master
2. Hit Flatten
3. To get back to normal go Zplugins > UV Master > Unflatten
4. To send back to Maya click export in the Tools panel.

Video 3.1: Unwrapping In ZBrush (1:48 mins)
 

Video Notes

Unwraping in ZBrush is easy.
1. Go to Zplugins > UV Master
2. Make sure “Symmetry” and “Use Existing UV Seams” is on
3. Click Unwrap
To Check the UVs
1. Go to Zplugins > UV Master
2. Hit Flatten
3. To get back to normal go Zplugins > UV Master > Unflatten
4. To send back to Maya click export in the Tools panel.

 

Maya Cleanup (4 mins)

This section covers a little bug in ZBrush where you may need to fiddle with fcurves, although rare. Otherwise it’s time to transfer the UVs back onto the rig.

Video 4.1: Bug Fixing When ZBrush Fails To Unwrap Properly (1:03 mins)
 

Video Notes

ZBrush has a great algorythym for unwrapping but sometimes it will fail. Simply try different UV placements while inside of maya. Make sure the seams will unfold. We can always try…
UV Editor > Polygons > Unwrap
That’s mayas rather inadequate unwrapper but it may help ZBrush out. As a last resort we can also re-pick our seams.

Video 4.2: Maya UV Transfer (2:18 mins)
 

Video Notes

In Maya we can use
Mesh > Transfer Attributes
To transfer the UVs of one model to another. We do this now if ZBrush has added extra edges because of NGons.
1. Select the Mesh with correct UVs then the mesh with NGons to transfer to.
2. Open Mesh > Transfer Attributes
3. Reset the settings
4. Turn “Color Sets” off and switch the sample space to “Local” and hit Apply (topology can work too)
This should transfer the UVs from the ZBrush mesh to our original. If we’ve already skinned our mesh this step will be to a duplicate of our original then see step 6 for applying the UVs to a skinned mesh.

Video 4.3: Tweak UVs in Maya (1:03 mins)
 

Video Notes

Tweak the UVs as desired in Maya, mostly this is just a matter of arranging the shells nicely. Or making adjustments to the scale of the UVs if desired.

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